There are disclosed in DE-A-36 27 431 mouldings of plastics material foam which is of different density in different layers of the moulding. Mouldings of this kind may be compacted to different extents over different areas, the density of the material being approximately identical in such differently compacted areas for areal units of identical size, whereas the thickness of the moulding varies. Such mouldings may be provided with coating layers of different structure, or to incorporate bearing elements in the mouldings. The materials used for the production of such mouldings consists of soft foamed material the cellular structure of which is compacted in marginal portions of the mouldings. Mouldings of this kind are used as sound damping elements although the mechanical strength of such mouldings is inadequate for some purposes.
For packaging purposes, in particular, composite panels or slabs of plastics materials may be filled with plastics material scraps. Because of the large number of open cells in a soft foamed material of this kind the individual parts of the expanded material granulate, or the individual parts of the filling material adhere to one another only via the cellular grid, so that the foamed material granulates, or the filling materials break off under stress. Such panels are of low mechanical strength.